<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <style>
      body {
        background-color: #3c6382;
        width: 100vw;
        height: 100vh;
        margin: 0;
        padding: 0;
      }
      :root {
        font-size: 14px;
      }
      main {
        width: 500px;
        height: 500px;
        border: 1px solid #ccc;
        margin-left: 2em;
        margin-top: 2em;
        overflow: hidden;
      }
      div {
        width: 100px;
        height: 100px;
        background-color: white;
        animation-name: change-border;
        animation-duration: 2s;
        animation-iteration-count: infinite;
      }

      @keyframes change-border {
        50% {
          border: 2px solid black;
          background-color: blueviolet;
        }
        100% {
          transform: scale(2);
          border: 2px dashed yellowgreen;
          background-color: red;
        }
      }
    </style>

    <main>
      <div></div>
    </main>
  </body>
</html>
